Concepts of Genetics 10th Edition Test Bank – William S. Klug

 

 

To Purchase this Complete Test Bank with Answers Click the link Below

 

https://tbzuiqe.com/product/concepts-of-genetics-10th-edition-test-bank-william-s-klug/

 

If face any problem or Further information contact us At tbzuiqe@gmail.com

 

Sample Questions 

 

 

Concepts of Genetics, 10e (Klug/Cummings/Spencer/Palladino)

Chapter 4   Extensions of Mendelian Genetics

 

1) With incomplete dominance, a likely ratio resulting from a monohybrid cross would be ________.

1.    A) 3:3

2.    B) 1:2:2:4

3.    C) 1:2:1

4.    D) 9:3:3:1

5.    E) 3:1

Answer:  C

Section:  4.3

 

2) A situation in which there are more than two alternative forms of a given gene would be called ________.

1.    A) multiple alleles

2.    B) alternation of generations

3.    C) codominance

4.    D) incomplete dominance

5.    E) hemizygosity

Answer:  A

Section:  4.5

 

3) A condition in which one gene pair masks the expression of a nonallelic gene pair is called ________.

1.    A) codominance

2.    B) epistasis

3.    C) dominance

4.    D) recessiveness

5.    E) additive alleles

Answer:  B

Section:  4.8

 

4) Typical ratios resulting from epistatic interactions in dihybrid crosses would be ________.

1.    A) 9:3:3:1, 1:2:1

2.    B) 1:1:1:1, 1:4:6:4:1

3.    C) 9:3:4, 9:7

4.    D) 1:2:2:4:1:2:1:2:1

5.    E) 3:1, 1:1

Answer:  C

Section:  4.8

 

 

5) With which of the following would hemizygosity most likely be associated?

1.    A) codominance

2.    B) incomplete dominance

3.    C) trihybrid crosses

4.    D) X-linked inheritance

5.    E) sex-limited inheritance

Answer:  D

Section:  4.11

6) A mutation in a gene often results in a reduction of the product of that gene. The term for this type of mutation is ________.

1.    A) codominance

2.    B) incomplete dominance

3.    C) gain of function

4.    D) multiple allelism

5.    E) loss of function or null (in the case of complete loss)

Answer:  E

Section:  4.1

 

7) Because of the mechanism of sex determination, males of many species can be neither homozygous nor heterozygous. Such males are said to be ________.

1.    A) dominant

2.    B) hemizygous

3.    C) recessive

4.    D) complementary

5.    E) None of the answers listed is correct.

Answer:  B

Section:  4.11

 

8) Assume that a dihybrid cross (AaBb × AaBb) is made in which the gene loci are autosomal, independently assorting, and incompletely dominant. What phenotypic ratio would you expect from such a cross? Just provide the ratio, not the phenotypes.

Answer:  1:2:1:2:4:2:1:2:1

Section:  4.3

 

9) Many of the color varieties of summer squash are determined by several interacting loci: AA or Aa gives white, aaBB or aaBb gives yellow, and aabb produces green. Assume that two fully heterozygous plants are crossed. Give the phenotypes (with frequencies) of the offspring.

Answer:  12 (white):3 (yellow):1 (green)

Section:  4.8

 

 

10) In mice, there is a set of multiple alleles of a gene for coat color. Four of those alleles are as follows:

 

C         = full color (wild)

cch       = chinchilla

cd        = dilution

c          = albino

 

Given that the gene locus is not sex-linked and that each allele is dominant to those lower in the list, diagram the crosses indicated below and give the phenotypic ratios expected from each.

 

(a) wild (heterozygous for dilution) × chinchilla (heterozygous for albino)

(b) chinchilla (heterozygous for albino) × albino

Answer:

(a)        Ccd × cchc  ⇒ 2 full color:1 chinchilla:1 dilution

(b)        cchc × cc ⇒ 1 chinchilla:1 albino

Section:  4.5

11) A mutant gene that produces brown eyes (bw) is located on chromosome #2 of Drosophila melanogaster, whereas a mutant gene producing bright red eyes, scarlet (st), is located on chromosome #3. Phenotypically, wild-type flies (with dull red eyes), whose mothers had brown eyes and whose fathers had scarlet eyes, were mated. The 800 offspring possessed the following phenotypes: wild type (dull red), white, scarlet (bright red), and brown. Most of the 800 offspring had wild-type eyes, whereas those with white eyes were the least frequent.

 

(a) Using standard symbolism, diagram the cross from the P generation (brown-eyed mothers scarlet-eyed fathers) and the F1 generation. Be certain to provide the alleles of the mutant genes.

(b) From the information presented above, how many white-eyed flies would you expect in the F2 generation?

Answer:

(a)  P     bw/bw; st+/st+     ×          bw+/bw+; st/st

F1:  bw+/bw; st+/st     ×          bw+/bw; st+/st

 

(b) 50

Section:  4.8

 

 

12) In the mouse, gene A allows pigmentation to be deposited in the individual coat hairs; its allele a prevents such deposition of pigment, resulting in an albino. Gene B gives agouti (wild-type fur); its allele b gives black fur.

 

(a) Diagram the cross between a doubly heterozygous agouti mouse mated with a doubly homozygous recessive white mouse.

(b) What would be the expected phenotypic ratio in the progeny?

Answer:

(a)        AaBb × aabb

(b)        1 (agouti):1 (black):2 (albino)

Section:  4.8

 

13) The trait of medium-sized leaves in iris is determined by the genetic condition PP’. Plants with large leaves are PP, whereas plants with small leaves are P’P’. A cross is made between two plants each with medium-sized leaves. If they produce 80 seedlings, what would be the expected phenotypes, and in what numbers would they be expected? What is the term for this allelic relationship?

Answer:  20 (large leaves), 40 (medium leaves), 20 (small leaves); incomplete dominance

Section:  4.4

14) The trait for medium-sized leaves in iris is determined by the genetic condition PP’. Plants with large leaves are PP, whereas plants with small leaves are P’P’. The trait for red flowers is controlled by the genes RR, pink by RR’, and white by R’R’. A cross is made between two plants each with medium-sized leaves and pink flowers. If they produce 320 seedlings, what would be the expected phenotypes, and in what numbers would they be expected? Assume no linkage.

Answer:

20 large, red

40 medium, red

20 small, red

40 large, pink

80 medium, pink

40 small, pink

20 large, white

40 medium, white

20 small, white

Section:  4.4

 

 

15) The following coat colors are known to be determined by alleles at one locus in horses:

 

palomino = golden coat with lighter mane and tail

cremello = almost white

chestnut = brown

 

The following table gives ratios obtained in matings of the above varieties:

 

Cross             Parents                     Offspring

 

1          cremello × cremello            all cremello

2          chestnut × chestnut            all chestnut

3          cremello × chestnut            all palomino

4          palomino × palomino         1/4 = chestnut

1/2 = palomino

1/4 = cremello

 

Assign gene symbols for the genetic control of coat color on the basis of these data.

Diagram the last two matings.

Answer:  C1C1 = cremello, C2C2 = chestnut, C1C2 = palomino

(3)        C1C1 × C2C2

(4)         C1C2 × C1C2

Section:  4.5

 

16) What is meant by the term epistasis? Distinguish between epistasis and dominance. Do not use examples in answering this question.

Answer:  Epistasis refers to a gene (or genes) of one pair masking the expression of a gene (or genes) at a different locus. Dominance refers to the form of expression of a gene in relation to its allele (or alleles). When an allele is dominant, the heterozygous combination is the same phenotypically as one of the homozygotes. Epistasis is a nonallelic interaction; dominance is an allelic interaction.

Section:  4.8

17) The following F2 results occur from a typical dihybrid cross:

 

purple:       A_B_         9/16

white:        aaB_         3/16

white:        A_bb         3/16

white:        aabb          1/16

 

If a double heterozygote (AaBb) is crossed with a fully recessive organism (aabb), what phenotypic ratio is expected in the offspring?

Answer:  3 (white):1 (purple)

Section:  4.8

 

 

18) Which types of ratios are likely to occur in crosses (F2) when one is dealing with two interacting, epistatic gene pairs?

Answer:  9:7, 9:3:4, 12:3:1, 15:1

Section:  4.8

 

19) Assume that a cross is made between two organisms that are both heterozygous for a gene that shows incomplete dominance. What phenotypic and genotypic ratios are expected in the offspring?

Answer:  1:2:1

Section:  4.3

 

20) Assume that a dihybrid cross is made in which the genes’ loci are autosomal, independently assorting, and incompletely dominant. How many different phenotypes are expected in the offspring?

Answer:  9

Section:  4.3

 

21) How many different alleles can a gene have?

Answer:  Theoretically, an extremely large number of possibilities exist. Various bases could change, giving a variety of alleles, and combinations of those changed bases could provide additional variety.

Section:  4.1

 

22) Assume that a dihybrid F2 ratio, resulting from epistasis, was 9:3:4. If a double heterozygote was crossed with the fully recessive type, what phenotypic ratio is expected among the offspring?

Answer:  1:1:2

Section:  4.8

 

23) Assume that a dihybrid F2 ratio, resulting from epistasis, was 15:1. If a double heterozygote was crossed with the fully recessive type, what phenotypic ratio is expected among the offspring?

Answer:  3:1

Section:  4.8

 

24) Name four modes of inheritance that are influenced by the sex of individuals.

Answer:  X-linked, sex-influenced, sex-limited, Y-linked

Section:  4.11, 4.12

25) The white-eye gene in Drosophila is recessive and sex-linked. Assume that a white-eyed female is mated to a wild-type male. What would be the phenotypes of the offspring?

Answer:  females wild type, males white eyed

Section:  4.11

 

 

26) Two forms of hemophilia are determined by genes on the X chromosome in humans. Assume that a phenotypically normal woman whose father had hemophilia is married to a normal man. What is the probability that their first son will have hemophilia?

Answer:  1/2

Section:  4.11

 

27) Two forms of hemophilia are determined by genes on the X chromosome in humans. Assume that a phenotypically normal woman whose father had hemophilia is married to a normal man. What is the probability that their first daughter will have hemophilia?

Answer:  0

Section:  4.11

 

28) State a significant difference between X-linked and sex-influenced inheritance.

Answer:  In X-linked inheritance, the gene in question is on the X chromosome; in sex-influenced inheritance, the gene is autosomal.

Section:  4.11, 4.12

 

29) Pattern baldness is determined by a single autosomal gene pair. When females are homozygous for this gene pair, can they show pattern baldness?

Answer:  Yes, but the phenotype is less pronounced and is expressed later in life.

Section:  4.12

 

30) Provide an example of sex-influenced inheritance.

Answer:  pattern baldness in humans, horn formation in sheep, certain coat patterns in sheep

Section:  4.13

 

31) What distinguishes sex-limited from sex-influenced inheritance?

Answer:  In sex-limited inheritance, expression is limited to one sex; in sex-influenced inheritance, expression differs between the sexes.

Section:  4.12

 

32) Comb shape in chickens represents one of the classic examples of gene interaction. Two gene pairs interact to influence the shape of the comb. The genes for rose comb (R) and pea comb (P) together produce walnut comb. The fully homozygous recessive condition (rrpp) produces the single comb. Assume that a rose-comb chicken is crossed with a walnut-comb chicken and the following offspring are produced: 17 walnut, 16 rose, 7 pea, 6 single.

 

(a) What are the probable genotypes of the parents?

(b) Give the genotypes of each of the offspring classes.

Answer:

(a)        Rrpp × RrPp

 

(b) R_Pp   (walnut)

      R_pp    (rose)

      rrPp     (pea)

      rrpp     (single)

Section:  4.8

33) Many of the color varieties of summer squash are determined by several interacting loci: AA or Aa gives white, aaBB or aaBb gives yellow, and aabb produces green. Crosses among heterozygotes give a 12:3:1 ratio. What type of gene interaction would account for these results?

Answer:  epistasis

Section:  4.8

 

34) A particular cross gives a modified dihybrid ratio of 9:7. What phenotypic ratio would you expect in a testcross of the fully heterozygous F1 crossed with the fully recessive type? Diagram the testcross using A,a,B,b as symbol sets.

Answer:  1:3   AaBb × aabb > AaBb, Aabb, aaBb, aabb

Section:  4.8

 

35) The enzyme glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as a recessive gene on the X chromosome in humans. A phenotypically normal woman (whose father had G6PD) is married to a normal man.

 

(a) What fraction of their sons would be expected to have G6PD?

(b) If the husband had G6PD, would it make a difference in your answer in part (a)?

Answer:

(a) 1/2

(b) no

Section:  4.11

 

36) A cross was made between homozygous wild-type female Drosophila and yellow-bodied male Drosophila. All of the resulting offspring were phenotypically wild type. Offspring of the F2 generation had the following phenotypes:

 

Sex                  Phenotype       Number

 

male                wild                   96

male                yellow                99

female             wild                 197

 

Based on this information:

(a) Is the mutant gene for yellow body behaving as a recessive or dominant?

(b) Is the yellow locus on an autosome or on the X-chromosome?

Answer:

(a) recessive

(b) X-chromosome

Section:  4.11

 

37) Below is a pedigree of a fairly common human hereditary trait in which the boxes represent males and the circles represent females. Shading symbolizes the abnormal phenotype.

 

Given that one gene pair is involved:

(a) Is the inheritance pattern X-linked or autosomal, recessive or dominant?

(b) Give the genotype of each individual in the pedigree. If more than one genotypic possibility exists, present all possible alternatives.

 

 

Answer:

(a) autosomal recessive

 

(b)

 

Section:  4.11

 

38) The genes for zeste eyes and forked bristles are located on the X chromosome in Drosophila melanogaster. Both genes are recessive. A cross is made between a zeste-eyed female and a forked-bristled male.

 

(a) If 200 offspring from this cross were obtained, present the expected number, sex, genotype, and phenotype in each class of the F1.

(b) If the F1 offspring were crossed to produce 800 flies of an F2 generation, present the expected number, sex, and phenotype in each class. Assume no crossing over.

Answer:

(a)        z+f/z f+      =          wild female     (100)

            z f+/Y        =          zeste male        (100)

 

(b)        z+f/z f+      =          wild female     (200)

            z f+/z f+     =          zeste female    (200)

            z+f/Y         =          forked male     (200)

            z f+/Y        =          zeste male        (200)

Section:  4.11

 

 

39) In a mating between individuals with the genotypes IAi × ii, what percentage of the offspring would be expected to have the O blood type?

Answer:  50%

Section:  4.5

40) In a mating between individuals with the genotypes IAIB × ii, what percentage of the offspring would be expected to have the O blood type?

Answer:  zero

Section:  4.5

 

41) If an X-linked disorder is lethal to the affected individual prior to the age at which one reaches reproductive maturation, the lethality will be expressed only in males. Why is this so?

Answer:  The only sources of the lethal allele in the population are heterozygous females who are “carriers” and do not express the disorder.

Section:  4.6, 4.11

 

42) Can females display pattern baldness?

Answer:  When females inherit the BB genotype, they can definitely express hair thinning; however, it is less pronounced than in males and occurs later in life.

Section:  4.12

 

43) Regarding the ABO blood group system in humans, if an individual is genetically IBi and yet expresses the O blood type, which genotype is it likely to have?

Answer:  hh (Bombay)

Section:  4.5, 4.8

 

44) With multiple alleles, there can be more than two genetic alternatives for a given locus.

Answer:  TRUE

Section:  4.5

 

45) With both incomplete dominance and codominance, one expects heterozygous and homozygous classes to be phenotypically identical.

Answer:  FALSE

Section:  4.3, 4.4

 

46) The ABO blood group locus in humans provides an example of epistasis.

Answer:  FALSE

Section:  4.5

 

47) Sex-limited inheritance is the same as sex-linked inheritance.

Answer:  FALSE

Section:  4.11, 4.12

 

48) A conditional mutant is one whose expression is influenced by some environmental condition.

Answer:  TRUE

Section:  4.13

49) A typical epistatic ratio is 9:3:4.

Answer:  TRUE

Section:  4.8

 

50) A 9:7 ratio indicates incomplete dominance.

Answer:  FALSE

Section:  4.3

51) Pattern baldness and hen/cock feathering in fowl are examples of X-linked inheritance.

Answer:  FALSE

Section:  4.12

 

52) Penetrance specifically refers to the expression of lethal genes in heterozygotes.

Answer:  FALSE

Section:  4.13